I am guessing is should be about as simple a request as you will see: just need someone to generate a model of a pyramid for shapeways. Dimensions of the square base is 4 inches a side, and each face a 55-55-70 triangle. If my high school math is correct, the vertical sides of the triangle would be 3.5 inches.

At that size, the object is going to be rather expensive.
You could save a large amount of money if you make the pyramid hollow.
But, that causes the question: What Material would you like to print it in?

Each material has a different wall thickness requirement.

The attached file is 4x4x3.5 and is completely solid.
It'd cost about $425.00 to print as a solid in WSF, possibly somewhere around $70 if it was hollow.

Edit: you actually want a pyramid that is 2.86" from the base to the peak.